Development of a TDR liquid level sensor

Abstract

Time Domain Reflectometry (TDR) is a pulse sampling technique that characterizes the distributed electrical properties of a transmission line. In liquid level measurement, the level probe acts as an open transmission line and the tank content become the transmission line?s insulation dielectric.? At each fluid interface, a change in dielectric constant of fluid surrounding the probe results in a change in electrical impedance that reflects a portion of the pulse amplitude to the TDR receiver.? Preliminary experimental results show that the pulse reflection timing information and the voltage amplitude can be used to accurately determine the fluid level or location of each fluid interface within the tank.